Knitting machine



Feb. 22, 1966 MCDQNOUGH 3,236,068

KNITTING MACHINE Filed Nov. 2, 1962 2 Sheets-Sheet 1 FIG.

Feb. 22, 1966 J. J. M DONOUGH 3,236,068

KNITTING MACHINE Filed Nov. 2, 1962 2 Sheets-Sheet z FIG.4. FIG. 5. F|G.6.

INVENTOR. JOHN J. MCDONOUGH I 3. vi- 21/ v ATTORNEYS United States Patent Williams, Incorporated, Laconia, N.H., a corporation of Massachusetts Filed Nov. 2, 1962, Ser. No. 235,018 9 Claims. (Cl. 66-111) This invention relates to knitting machines, and particularly to the control of latches of needles in circular knitting machines.

When, in a circular knitting machine having latch needles, the needles are raised high enough for their pivoted latches to clear the stitch loops, guards are generally provided to prevent accidental closing of the latches and subsequent failure of the needles to take yarn as they are thereafter lowered. In circular hosiery machines the guard is usually in the form of a latch ring of slightly larger diameter than the circle of needles which it surrounds. However, one or more openings in the ring are necessary for passage of the yarn feeding fingers, and in order that the latches may be guarded at these points movable gates or gap closers are commonly used. While these add more satisfactory protection, they not only require operating elements, but if they fail to move out of action at the proper time there is likely to result serious damage to the yarn fingers and related parts. To avoid their use, there have been preferentially supplied angularly arranged cam surfaces on the latch ring at the sides of the opening or openings therein, these serving as cams for opening latches that may have swung to a horizontal position, or for closing those that may have swung higher, thereby to prevent damage. In the latter case, the closing of latches will generally produce dropping of stitches, unless a subsequent latch opener is used, but this possibility of a defective product is much to be preferred in contrast with mechanical damage, if only to a needle.

The needles generally involved in the mispositioning of latches are those raised to an inactive level when reciprocatory knitting is taking place for the formation of heels and toes. It has generally been considered that the mispositioning of latches causing closing was caused by slight vertical movement or disturbance of the needles coupled with centrifugal action on their unguarded latches. However, it now appears upon study of the misoperations that it is more likely that needle magnetization is involved to a major extent. It is well-known that some needles in a machine may become slightly magnetized. When magnetization is very strong, a needle latch may be caused to extend substantially at right angles to the needle shank. However, more usually, and probably more troublesome, is the situation in which needles become only slightly magnetized. Under these conditions, particularly as they move outwardly under centrifugal action in a rotary cylinder machine, they will be attracted to a latch ring and ride on its internal cylindrical surface, though at this time in well-opened position. But once they engage the latch ring, they tend to remain in contact therewith, and as they leave the latch ring at a feed opening therein, they will then tend to follow the lower cam surface of the latch ring at the edge of the opening and be raised thereby. This raising as they leave the cam circumferentially will frequently cause them to swing high enough to be closed by the upper cam surface at the opposite side of the opening. This is probably particularly due to the fact that the needles are moving rapidly and the latches in riding up the cam surface which they ultimately leave have a minor inertia which will carry them slightly above the theoretical leaving level.

Patented Feb. 22, 1966 The primary object of the present invention is to effect latch movements and positioning to avoid latch closure, and consequent dropping of stitches, in an arrangement of the general type described in which the use of gap closers is avoided. In brief, this is accomplished by causing latches which may be magnetically following the inner surface of the latch ring to be kicked inwardly toward open position before the opening in the latch ring is reached. Briefly stated, this is effected by providing the latch ring at proper locations with depressions into which the latches may enter, the trailing ends of these depressions acting as cams which, considering the rapid movements of the needles, impart inward movement to the latches with suflicient sharpness of action to cause the latches to be disengaged from the latch ring. When the magnetization is weak, as is usually the case, the separation of the latches from the latch ring is sufiicient to avoid their reattraction to the latch ring, and consequently they will pass the opening in proper opened position, retaining this position sufiiciently long that as they pass the farther end of the opening the latch ring will maintain them in open position.

The foregoing general object and other objects relating to details in construction and operation will become apparent from the following description, read in conjunction with the accompanying drawings, in which:

FIGURE 1 is a developed view of the cams and other elements cooperating with the needles, looking outwardly from the axis of a rotating needle cylinder;

FIGURE 2 is a plan view of a latch ring embodying the invention;

FIGURES 3, 4 and 5 are fragmentary axial sections taken on the planes indicated at 33, 44 and 55, respectively, of FIGURES 1 and 2; and

FIGURE 6 is a similar axial section taken on the plane indicated at 66 in FIGURES 1 and 2 but merely illustrative of the undesired action occurring in the arrangements heretofore used.

While the invention is generally applicable to circular knitting machines of both rotary cylinder and stationary cylinder types, and particularly to hosiery knitting machines in which the problem outlined is primarily likely to occur, and whether such machines are of single feed or multifeed types, it will be described with particular reference to a two-feed hosiery knitting machine of rotary cylinder type. The invention is not specifically concerned with the details of operation of such a machine, and, consequently, the disclosure herein is limited to those parts which are more or less directly concerned with the subject matter of the invention. The particular machine illustrated by way of example is of the type disclosed in McDonough Patent 2,902,845 to which reference may be made for more detailed aspects of operation. This machine is of the type in which two feed knitting is involved not only during rotary knitting but also during the reciprocatory knitting of heel and toe pockets.

The needle cylinder 2 is arranged for rotation and reciprocation in the usual fashion and is slotted for the mounting of the needles 4 which have the usual hooks 6 and latches 8 pivoted at 10 and are provided with butts 12 of various lengths for needle control and selection in usual fashion. Conventional sinkers 14 cooperate with the needles.

The latch ring 16, which is conventional except for the modifications involved in the present invention is of multiple part type presenting interiorly to the needles a cylindrical surface interrupted only at the locations of the throat plates 18 and 20 whereat fingers 22 and 24 are provided to feed yarns to the needles in conventional fashion. As is usual, multiple fingers may be provided at each feed, these being selectively located in operative feeding 3 conditions. The result is that gaps 26 and 28 exist in the latch ring, these providing for insertion and withdrawal of the feeding fingers which are pivoted so that their active ends have vertical movements.

A central cam element 30 provides a pair of cam sur faces 32 and 34 acting on needle butts, the surface 32 providing the stitch cam at the first feed during rotary knitting and forward reciprocatory strokes, and the surface 34 providing the stitch cam at the second feed during reverse strokes. A cam 36 provides the cam surface 38 acting as the stitch cam at the second feed during rotary knitting and forward reciprocatory strokes, while the cam 40 provides the cam surface 42 acting as the stitch cam at the first feed during reverse strokes of reciprocatory knitting. Raising pickers 46 and 48 serve to raise needles during narrowing in the formations of heel and toe pockets, and a lowering picker 50 serves to restore inactive needles to active condition during widening of such pockets. Needle paths A and B are illustrated as they occur during reciprocatory knitting of heel and toe pockets. Active needles are in the path indicated at A, and inactive needles are in the path indicated at B. Cams 51 and 53, respectively, are provided as usual to raise needles as a group to the inactive level B and to restore them as a group to the active paths.

T o the extent of what has been described, the arrangement and the operation of the parts illustrated are completely conventional and need not be further described. The present invention is concerned particularly with the control of latches of the needles following the inactive path B.

Referring, now, particularly to the latch ring as shown in FIGURES l and 2, conventional aspects thereof will now be described. Considering the direction of rotary knitting from right to left, as indicated by the arrows in FIGURE 1, the latch ring terminates at the gap 26 in upper and lower cam surfaces 52 and 54 sloping as illustrated and meeting at a radially extending edge 56. When the needles are following the inactive path B, the latch pivots are at a level slightly below the level of the edge 56. At the far side of the opening 26 the latch ring section is similarly provided with cam surfaces 58 and 60 meeting at the edge 62. At the gap 28 this same latch ring section is provided with the cam surfaces 64 and 66 meeting at the edge 68. At the left hand side of the gap 28 the latch ring is provided with the further cam surfaces '70 and 72 meeting at the edge 74. The corresponding cam surfaces just described are similar, and the edges 56, 62, 68 and 74 are at the same level.

Considering, now, the usual operations heretofore involved, which utilize the cam surfaces and edges just described, conditions of operation may be described as follows:

Assuming no magnetization of a needle following the inactive path B, and assuming motion toward the left through the cams as viewed in FIGURE 1, the needle latch would be open as it moved past the cylindrical surface 76 of the latch ring. If the latch pivot happened to have low friction, the latch by centrifugal action might have its spoon running in contact with the surface 76. It would then pass the cam surface 54 at a level below the edge 56, and thereafter might move outwardly to the horizontal position due to centrifugal force. As it moves across the gap 26, however, its latch would be below the level of the edge 62, so that the cam 60 would move it downwardly toward a further open position. This same normal type of operation would be repeated at the location of the gap 28.

Still assuming no magnetization of the needle, it might happen that for some reason, such as vibration, a latch after entering the gap 26 might move upwardly beyond its horizontal position so as to reach the next portion of the latch ring at a level above the edge 62. In this case it would be cammed toward closed position by the cam 58. This closed condition of the latch may be rectified later by its being opened by centrifugal action or by jarring of the needles, but even if it persists to the time when the needle is again restored to action, the only result will be a defect, and not mechanical damage. Similar actions would, of course, occur at the other feed and during reciprocatory strokes in both directions.

The likelihood of misoperation is much increased if a needle is magnetized. For consideration of this reference may be further made to FIGURE 6. If the magnetization, as usual, is slight, if the latch is not engaged with the latch ring surface 76 it is not likely that it will be attracted thereto because of even slight static friction at the latch pivot. But if the latch does engage the surface '76, it will adhere magnetically thereto. As the latch passes the edge 54, since contact is maintained, it will not normally disengage the latch ring because even a slight magnetic force will maintain engagement even if insufficient to produce initial engagement. Accordingly, as indicated in FIGURE 6, the latch is very likely to move upwardly in contact with the surface 54, leaving this surface only at the edge 56 due to circumferential movement of the needle. However, at the moment of leaving the surface 54 at the edge 56 it will be actually swinging upwardly at a considerable angular rate due to the rapid circumferential movement of the needle, and consequently as it leaves this edge it may, by its own inertia, rise somewhat higher. If it remains in this higher position, it will reach the section of the latch ring beyond the gap 26 at a level above the edge 62 so that it will ride up the surface 58, i.e., the intersection of this surface with the cylindrical surface of the latch ring section. Thus it will be cammed toward closed position. It may, further, be jarred by the impact toward almost fully closed position so as not to continue to engage the latch ring section. The result will be a dropped stitch and fault in the fabric.

From the foregoing it will be evident that the likelihood of latch closure is quite substantially increased by needle magnetization. This is in comparison with the relatively unlikely misoperation due to merely mechanical causes.

The invention is directed primarily to minimizing misoperation due to magnetization. The situation has been found to be effectively cured by a relatively simple expedient: that of providing in the surface 76 of the latch ring a depression 78 at the location opposite the latch which terminates in an outwardly directed cam surface 80 the form of which is illustrated most clearly in FIGURE 2. This cam surface desirably has a relative rapid rise in an inward direction. The action then is as follows, with particular reference to FIGURES 3, 4 and 5. FIGURE 3 shows the condition existing as a magnetized needle approaches the depression. Its latch 8 is magnetically held against the cylindrical surface 76 of the latch ring. As the position of the depression 78 is reached, the magnetic attraction persists, and the latch will be swung outwardly so as to continue engagement, now with the surface of the depression 78. As the latch reaches the cam portion 80 of the depression, it is moved outwardly and downwardly toward open position. If the movement of the needle cylinder was quite slow, the latch might well continue to engage the latch ring surface after being acted upon by the cam 80; but during normal operation, the needle will be moving so rapidly that the rather abrupt action of the cam portion 80 will impart a kick to it so that it will be snapped away from the latch ring surface as illustrated in FIGURE 5. As already pointed out, the magnetization of needles is generally rather weak, and once the latch leaves engagement with the latch ring the magnetic attraction will be so low that it is unlikely that it will be reattracted thereto. Accordingly, once it is snapped away from the latch ring it will generally retain its open position. Furthermore, it will be noted that the cam portion 80 of the depression 78 terminates immediate- 1y preceding the lower portion of the cam surface 54, and since the latch is at least almost fully opened, a time element is involved in that before the latch could bounce back to an outward position it will have passed the surface 54 so as not to be in sufficiently close position relative thereto to be reattracted. Accordingly, once it is disengaged from the latch ring it will not be reattracted thereto and will remain well opened.

To provide the same action at the other gap 28 and at both gaps during reverse strokes, depressions 82 and 88 are similarly provided, the depression 82 having two cam portions 84 and 86, and the depression 88 having the cam portion 90. The actions of these are the same as just described and need not be repeated.

As will be evident from the foregoing a simple modification of the conventional latch ring construction results in elfective avoidance of the difficulties arising from needle magnetization.

It will be evident that various modifications may be made in accordance with the invention Without departing from the scope thereof as defined in the following claims.

What is claimed is:

1. A circular knitting machine comprising a needle cylinder, latch needles independently movable in said cylinder, elements cooperating with said needles for the formation of stitches, a latch ring surrounding said needles and provided with a gap for the feeding of yarn, and means for imparting relative rotational movements to said needle cylinder and latch ring, said latch ring being provided with a cam portion engageable with latches of needles to impart thereto movements in opening direction as the needles and latch ring gap approach each other, thereby to prevent latches from magnetically adhering to the latch ring at an edge of said gap.

2. A circular knitting machine comprising a needle cylinder, latch needles independently movable in said cylinder, elements cooperating with said needles for the formation of stitches, a latch ring surrounding said needles and provided with a gap for the feeding of yarn, and means for imparting relative rotational movements to said needle cylinder and latch ring, said latch ring being provided with a cam portion engageable with latches of needles to impart thereto movements in opening direction as the needles and latch ring gap approach each other, thereby to prevent latches from magnetically adhering to the latch ring at an edge of said gap, said cam portion being provided by the edge of a depression in the latch ring.

3. A circular knitting machine comprising a needle cylinder, latch needles independently movable in said cylinder, elements cooperating with said needles for the formation of stitches, a latch ring surrounding said needles and provided with a gap for the feeding of yarn, and means for imparting relative rotational movements to said needle cylinder and latch ring, said latch ring being provided at each side of said gap with a cam portion engageable with latches of needles to impart thereto movements in opening direction as the needles and latch ring gap approach each other, thereby to prevent latches from magnetically adhering to the latch ring at an edge of said gap.

4. A circular knitting machine comprising a needle cylinder, latch needles independently movable in said cylinder, elements cooperating with said needles for the formation of stitches, a latch ring surrounding said needles and provided with a gap for the feeding of yarn, and means for imparting relative rotational movements to said needle cylinder and latch ring, said latch ring being provided at each side of said gap with a cam portion engagealble with latches or needles to impart thereto movements in opening direction as the needles and latch ring gap approach each other, thereby to prevent latches from magnetically adhering to the latch ring at an edge of said gap, each of said cam portions being provided by the edge of a depression in the latch ring.

5. A circular knitting machine comprising a needle cylinder, latch needles independently movable in said cylinder, elements cooperating with said needles for the formation of stitches, a latch ring surrounding said needles and provided with a gap for the feeding of yarn, means for raising needles to a cleared inactive level, and means for imparting relative rotational movements to said needle cylinder and latch ring, said latch ring being provided with a cam portion engageable with latches of inactive needles to impart thereto movements in opening direction as the needles and latch ring gap approach each other, thereby to prevent latches from magnetically adhering to the latch ring at an edge of said gap.

6. A circular knitting machine comprising a needle cylinder, latch needles independently movable in said cylinder, elements cooperating with said needles for the formation of stitches, a latch ring surrounding said needles and provided with a gap for the feeding of yarn, means for raising needles to a cleared inactive level, and means for imparting relative rotational movements to said needle cylinder and latch ring, said latch ring being rovided at each side of said gap with a cam portion engageable with latches of inactive needles to impart thereto movements in opening direction as the needles and latch ring gap approach each other, thereby to prevent latches from magnetically adhering to the latch ring at an edge of said gap.

7. A circular knitting machine according to claim 2 wherein said depression is located above the lower edge of said latch ring.

8. A circular knitting machine according to claim 4 wherein said depressions are located above the lower edge of said latch ring.

9. A circular knitting machine according to claim 5 wherein said cam portion is provided by the edge of a depression in the latch ring located above the lower edge thereof.

References Cited by the Examiner UNITED STATES PATENTS 1,183,604 5/1916 Swinglehurst 661l1 X 2,736,177 2/1956 BriStOW 66-11l X DONALD W. PARKER, Primary Examiner. 

1. A CIRCULAR KNITTING MACHINE COMPRISING A NEEDLE CYLINDER, LATCH NEEDLES INDEPENDENTLY MOVABLE IN SAID CYLINDER, ELEMENTS COOPERATING WITH SAID NEEDLES FOR THE FORMATION OF STITCHES, A LATCH RING SURROUNDING SAID NEEDLES AND PROVIDED WITH A GAP FOR THE FEEDING OF YARN, AND MEANS FOR IMPARTING RELATIVE TO ROTATIONAL MOVEMENTS TO SAID NEEDLE CYLINDER AND LATCH RING, AND LATCH RING BEING PROVIDED WITH A CAM PORTION ENGAGEABLE WITH LATCHES 